Effect of osmoconditioning upon seed germination of sorghum (Sorghum bicolor (L.) Moench) under low temperatures

The response of germination to temperature and to seed osmopriming among ten sorghum genotypes of diverse genetic background was examined in order to assess the genetic variability and the possibility of improving germination performance by means of seed water manipulation. Genotypes were tested in combination with seven germination temperatures (ranging from 4° to 25°C) and two seed treatments (no treatment (control) and osmopriming (250 g 1-1 of PEG at 15°C for two days)). The response of germination rate to temperature among genotypes and the thermal time to 50% germination, for each seed treatment were examined. The treatment of the seeds in osmotic solution was effective on promoting higher germination percentages at lower temperatures (ranging from 8° to 10°C). Osmotic treatment reduced base temperature by almost one degree centigrade compared to control. Differences among genotypes on the base temperature for germination have been found, which is promising for the development of cold tolerant sweet and fibre sorghum genotypes